Strong pairing in mixed dimensional bilayer antiferromagnetic Mott insulators

TL;DR

This paper proposes a novel high-temperature pairing mechanism in mixed-dimensional bilayer antiferromagnetic Mott insulators, leading to tightly bound, highly mobile pairs, with potential realization in ultracold atom experiments.

Contribution

It introduces an efficient pairing mechanism in bilayer Hubbard models, resulting in binding energies proportional to the cube root of the hopping amplitude, and demonstrates formation of mobile, tightly bound pairs.

Findings

Binding energies scale as t^{1/3}

Formation of highly mobile, tightly bound pairs

Mechanism applicable to ultracold atom experiments

Abstract

Interacting many-body systems combining confined and extended dimensions, such as ladders and few layer systems are characterized by enhanced quantum fluctuations, which often result in interesting collective properties. Recently two-dimensional bilayer systems, such as twisted bilayer graphene or ultracold atoms, have sparked a lot of interest because they can host rich phase diagrams, including unconventional superconductivity. Here we present a theoretical proposal for realizing high temperature pairing of fermions in a class of bilayer Hubbard models. We introduce a general, highly efficient pairing mechanism for mobile dopants in antiferromagnetic Mott insulators, which leads to binding energies proportional to $t^{1/3}$, where $t$ is the hopping amplitude of the charge carriers. The pairing is caused by the energy that one charge gains when retracing a string of frustrated bonds created by another charge. Concretely, we show that this mechanism leads to the formation of highly mobile, but tightly bound pairs in the case of mixed-dimensional Fermi-Hubbard bilayer systems. This setting is closely related to the Fermi-Hubbard model believed to capture the physics of copper oxides, and can be realized by currently available ultracold atom experiments.